How a modified Nissen procedure works: a mechanistic study using intraoperative esophageal high-resolution manometry.

Objective: We aimed at demonstrating how a modified Nissen procedure works by analyzing intraoperatively the variations of the low esophageal sphincter pressure values using high resolution manometry.

Methods: This study included 15 patients with documented gastroesophageal reflux disease who underwent a laparoscopic modified Nissen procedure. Data regarding the changes in the pressure values were recorded at each step of the procedures using high resolution manometry and after the progressive insufflation of air in the stomach. Categorical data were compared between the preoperative and postoperative periods using Fisher's test, and continuous data were compared using Mann-Whitney U non-parametric test. Preoperative versus postoperative variations in continuous data were assessed using Wilcoxon's non-parametric test for paired data.

Results: Intraoperative manometric data showed a rise of basal LES pressure until the creation of the wrap. An evident increase of pressure values was recorded after gastric air insufflation, as consequence of the increase of intragastric pressure. No intraoperative and postoperative complications were observed. All patients experienced a significant reduction in terms of intensity and frequency of gastroesophageal reflux symptoms and no patients complained of dysphagia.

Conclusions: Intraoperative high resolution manometry was feasible in all patients and demonstrated that the modified Nissen procedure works by increasing the LES pressure in response to gastric distension, without impeding the progression of the bolus into the stomach.